I thought you enjoyed sitting in the sauna then rolling naked in the snow...
Hey! That guy is *Norwegian*. They don't have saunas. The Norwegians bathe in oil. The poor Norwegians have the biggest oil reserves in Europe and then we hear them complain about the climate, which is not even cold. Damn those ridiculous oily Norwegians!
No, just kidding. I love cold! The coldest nude-rolling-in-the-snow I've had was at about -50 C and I still liked that. But this winter has been about the crappiest one ever, it's something like -0.5 C right now.:-/
And, as you well know, some cultures will eat almost anything,
In fact, most cultures will eat anything, as the international success of McDonalds well proves.
Finns will eat a bitter oil,
Well, since this already degenareted to the level of national slurs... I can see that you learned to read at an American school.
The rapeseed oil that I use is not bitter. Not even fresh rapeseed tastes very bitter (I grew up in the middle of rape fields, so I tried rape many times and actually found it rather pleasant) (no puns intended, here, naturally), not even the varieties that weren't grown for human consumption. IMHO, of course.
but Americans and Canadians won't touch it, except in the altered form marketed as Canola Oil.
Americans won't touch rapeseed oil, unless someone sells it to them as something else than rapeseed oil? OK, I can believe that...
The difference between what is today called "canola oil" and "rapeseed oil" in North America is that canola oil is marketed for cooking and rapeseed oil is marketed (if it is marketed) for industrial use. For this reason, the oil needs to meet some FDA/[insert Canadian equivalent] restrictions before it can be called canola oil. The reason the-breed-originally-called-Canola was bred that a certain acid in rapeseed oil was considered unhealthy in the US, so someone set out to breed a variety that would automatically have a low amount of that acid. The name was catchy (and the old name probably gave the marketing drones nightmares), so nowadays all rapeseed oil sold for human consumption is called canola oil in North America.
That's it. Canola isn't "an altered version of rapeseed oil", it's just rapeseed oil that's deemed to have acceptable levels of that particular acid (and everything else someone might have considered harmful to humans). Dunno about English speaking countries in general, but here in Finland we don't feel like we need a separate word for "rapeseed oil that's approved by the bureaucrats". (It might also have something to do with the fact that our words for rape and rape don't resemble each other.)
and that rapeseed oil was used to lubricate steam engines.
Sure. I don't understand why it so often surprises people, but many things that are useful in the kitchen are also useful for other things. There's no law of chemistry that states that industrial lubricants have to taste bad.
Rapeseed is a plant that made an oil that was too bitter to eat. Rapeseed oil was commonly used to lubricate steam engines until the 1940's. Recently, Canadian farmers have bred the bitterness out of the oil to make an edible product called Canola. (Canadian Oil).
I see reading a few bits from Wikipedia and answering without actually knowing anything about the subject now gets you modded up. See the article on rapeseed to actually learn something about the subject; it's less nonsensical.
Rapeseed oil has traditionally been the most important cooking oil in many countries, especially here in the north where you can't grow corn, peanuts, soybeans, palm trees or pretty much anything (I live in Finland...). You need some processing to make it edible, but it's been one of the most significant sources of vegetable oil long before Canola was bred. Most of the world hasn't even heard of canola oil but is happy to eat rapeseed oil. I just fried some stuff using some.
The Higgs Boson is a critical part of Quantum Mechanics
No. The Higgs is a critical part of the Standard Model, that is, the best current theory of particle physics. It's not a part of the basic theory of quantum mechanics at all. If the Higgs is not found, that'll mean trouble for the Standard Model but not at all for quantum mechanics.
and the boson is not found, the basic foundation of quantum mechanics will have to be questioned,
Again, no. Finding or not finding the Higgs will not say anything at all about quantum mechanics, it will only say something about the Standard Model of particle physics. The SM is naturally built on quantum mechanics, but proving it wrong will not say anything about quantum mechanics; there's still no reason to assume that the correct theory wouldn't be some other theory based on quantum mechanics.
For comparison, think of Newton. He introduced both the general laws of mechanics (the stuff about forces and such) and a particular theory of a phenomena, gravity, in the context of his new mechanics. If it would've turned out that his law on the force of gravity had been wrong, it wouldn't have yet meant that there would've been something wrong with the concept of force. His theory of gravity was a separate theory expressed in the context of his theory of mechanics, just like the theories of particle physics are separate theories expressed in the context of quantum mechanics.
Quantum mechanics is a very abstract and general theory, the most general theory we have (and *much* more general than classical mechanics). It's just a set of axioms that dictate how the laws of nature must work; the principles of quantum mechanics are actually completely indifferent to what the world is "made of", "particles" or whatever. You can build a wild variety of theories on quantum mechanics, using any entities you can mathematically dream of as the basic building blocks (for example, "particles" as they do on your first QM course or "fields" as they do on your particle physics course).
How does one account for the popularity and prominence of the Communists in Finland after World War?
Err... what prominence? The countries where the communists were truly prominent after WWII ended up in the East bloc; Finland didn't.
Some communists were able to achieve some power immediately after the War with the help of some Soviet meddling, for example through the Allied Control Comission (which in Finland was almost completely made up of Soviet representatives - the other Allies had no demands for Finland), but they never managed to bring Finland to a revolution (and, unlike the communists in some other countries, they had less of an interest in a violent revolution that would've taken Finland into the Soviet Union). Some years after the war it was clear that the communists were no real political power.
There was, still, a rebound in radical leftism after the Continuation War. It's not so hard to explain at all. For example, most of the Finnish cultural elite had been extremely unhappy about fighting together with the Nazis and when the whole truth about them got out (during war time the anti-Nazi press had been silenced, so people didn't know that much about the Germans), they were absolutely shocked. It's not very surprising that many people felt the need to distance themselves from the Nazis as much as possible, even if it meant getting "closer" to the ideology of Finland's worst enemy.
Althought recently in decline, in the last parliamentary elections, the Left Alliance, the successor to the Communist Party, got close to 10% of the vote.
...whereas the Communist Party got something like 0.7 %.:-)
The Left Alliance isn't really "the successor to the Communist Party", but a successor to several leftist parties, the Communists being the most radical ones. The most radical parts of the Communist Party refused to join the Left Alliance and set up the Communist Party again (so there isn't a "successor" to it as such, it's just that almost all of the "ex"-communists joined the LA).
It would be silly to call the Left Alliance people "communists" (but IMHO still not at all silly to call them dumbasses:-)). The actual Communist Party is nothing but a joke today - Donald Duck and the female private organ probably get more votes than the communists.
I mean that the military service is only 6 months, you can spend most of the weekends at home, you can bring your own mobile phone there (and use it to IRC/chat/surf/whatever), you can use the computers at the canteen and so -- still some kiddies suffer from Internet addiction.
What the **** we are going to do when the Russians come?:)
We'll offer them some coffee, let them play Tetris on our mobile phones and stick a 20 euro bill in their pockets if they promise to go home.
I mean, 20 euros ought to be enough for any Russian soldier...
The Finnish performance in WW2 was mainly due to four factors.... I don't think that the "quality of the soldiers" was that much different.
Actually, the quality of soldiers was different, or rather the quality of the leadership. The Finns still had a lot of officers who had training and field experience from the old Imperial Russian army, but on the Russian side that talent had all been lost in the revolution, and even after that Stalin's purges had taken a heavy toll on the Red Army. Stalinism massively hurt almost everything important to any Soviet efforts, from science to the military, when the political leadership interfered with everything and replaced competent people with idiots that made bigger promises.
And...
Four, defending your homeland gives you some extra boost compared to simply invading some other country.
The Soviets had also expected there to be a lot of Finnish communists who would defect and greet the Red Army as some great liberator, but there weren't because the Soviets had already killed them. There had been a lot of communists in Finland, but most of them had moved to the Soviet Union (this was not a big deal for a Finnish communist: there were a lot of ethnic Finns living in the Soviet Union, so it was just the border between a capitalist bourgeois democracy and the great socialist wonderland) and the paranoid Soviets had, of course, executed almost all of them as spies or unreliables. (The rumors that not all was well in the wonderland
then, naturally, contributed a lot to the Finnish will to fight; for the Finns, it was not just Finland that was at stake, but the fate of Finns as a people.)
Totalitarianism has a real habit of working against itself...
Hi, I live in Canada and I've always wondered why we didn't have a fridge that would take advantage of the outside temperature ?
You don't? Well, we certainly do over here in Finland! I just cooled down a pizza outside. Unfortunately (yeah right, mwahaha!) it's not cold enough to properly cool down beer right now, but when it is, we do that, too.
I mean, when it gets down to -20s celcius and you spend a lot of energy heating your house to +20 celcius, then you spend some more energy to cool down the fridge inside the house (although it actually participates in heating up your house), it sounds kind of ridiculous, don't you think ?
No, it doesn't. Your fridge (or anything else) cannot destroy energy, so every bit of energy taken from the electrical socket must end up in the house - and the only thing that a fridge really produces is heat (it doesn't radiate away any energy as light, for example). You have to remember that when you put energy in an object to heat it, you take energy out from it to cool it. If you were to use the outside air to cool things, you'd actually be throwing away some heat that you've paid for - what you suggest would be a waste of energy, not the other way around.
(Of course, it might make sense for you personally to cool things outside, depending on how you're heating your house. My apartment is heated by some waste heat from some factory or power plant or something like that, so I'm not actually directly paying for the amount of heat; it's included in the rent. Cooling things outside would be economical for *me*, but it's always unecological. Not that it matters much either way, but...)
Maybe it wouldn't be of much use for anyone but canadians, russians, norvegian and the like, but still...
Not for most Norwegians. I think most of them live on the coast and there they have the Gulf current heating up the place, so they don't have proper freezing weather. Besides, the Norwegians don't have to worry about some tiny energy savings - they have oil to burn. (Way too much oil! Damn we hate those Norwegians.)
I put my PC in the fridge and have extra long cables!
Hmm. The noise from my PC has often made me want to throw it out the window. Now it occures to me that, since I live in Finland, this might actually be a *great* idea!
"general relativity", which is obviously as much at odds with quantum mechanics as any classical theory is.
So special relativity, being non-quantum, is also as much at odds with quantum mechanics as any classical theory too?
No.
Woh, deep!
Not really; this is just an issue with terminology. What's a classical theory and what's a quantum theory? Well, I don't want go into that much detail on a web forum, so lets just grab some simple example, like the point particle.
The classical (Newtonian or relativistic) theory of a point particle is just the "physics" they tought you in high school. The basic objects in this theory have some property called "position" and another one called "velocity", the speed at which the "position" changes; to completely describe one such object you need to specify its "position" with three numbers (assuming we're doing 3D physics) and its "velocity" with another three numbers. That's how you describe a system of classical point particles. Then, when you want to include some actual physics, you introduce "forces" between the particles and apply Newtons laws to see how their velocities change due to these forces.
The quantum theory of point particles still consists of these same properties, "position" and "velocity", but in a very different way. Briefly put, a quantum particle doesn't have a specific position or velocity, but can be in a "superposition" of different positions -
you can have a particle sitting here with 36 % probability and there with 24 % probability and so on (and then you'll also have to think of something called the "phase" to completely describe the system, but lets not go into that now).
So, in QM, position and velocity are no longer the basic quantities that you'd directly solve from the laws of physics. Instead, the basic law, "the Scrodinger equation" (for point particle nonrelativistic QM), only gives a "wave function", a mathematical object from which you can calculate the probabilities of observing the particle in different positions and with different velocities. (Then, if you wanted to include some actual physics in the picture, you'd insert something representing interactions in the Schrodinger equation and solve the wave functions.)
That's how it works for the point particle. But it works the same way for any sort of a system. For example, we might have objects called "fields", which are things that have some value (which might a single number, a vector or something else) at every point in spacetime. To handle this classically, you need an infinite number of numbers (much more than the 2*3 you need with point particles!), but otherwise it works similarly. Again, the quantum version of is different, in the expected way (although in the actual study of quantum fields you'd run into many unexpected things).
The point is, you have a bunch of numbers (called "degrees of freedom") that describe some sort of a system; once you have decided in this way what kind of a system you have, you can do either classical mechanics or quantum mechanics with it. (Of course, it really isn't this simple, but I just want to bring out a certain point, so maybe a little simplification can be allowed.)
Now, is special relativity a classical or a quantum theory? You can sort of argue that it's neither: it's just a statement about the (fixed) geometry of spacetime. There are no numbers, "degrees of freedom", that go along naturally with it. It doesn't concern any sort of a system; it just tells you a fixed thing, a symmetry that you need to include in your equations if you want them to comply with this "special relativity". In this sense you can talk of "special relativistic QM" or "special relativistic mechanics" (or "special relativistic anything") and mean the same thing - that you're doing physics in a "special relativistic" ("Minkowskian") spacetime.
What's general relativity, then? Well, it's just the same as SR, but this time the geometry of spacetime is dynamical i
Don't forget that you also need to include the magnetic monopole current term
I didn't forget. Did you notice that part where I said that "...then we'll just have to include these magnetic charge/current terms (which are normally set to zero) in Maxwells equations as well."
Doing so would destroy EM's status as a pure tensor, a geometric object. Allowing the EM potential, A, as a tensor (rank 1 and covariant) yields the Maxwell equations plus conservation of charge as theorems; they become Bianchi identities. In other words, the nonexistence of magnetic monopoles is a mathematical truth if general relativity is more than just another system of epicycles.
If I read you correctly, you'd want to assume that electromagnetism can be built on a single vector potential and then conclude (from the theory that you get this way) that magnetic monopoles don't exist. Sorry, but this is utter nonsense. If you had taken a basic course on electromagnetism, you'd know that the ability to describe electromagnetism with a single vector potential depends on the fact that the divergence of the magnetic field vanishes and it - just like I said in my previous post - only vanishes if magnetic monopoles don't exist.
In other words, assuming that one vector potential is enough is equivalent to assuming that magnetic monopoles don't exist. Your argument really says nothing else than "if you assume that magnetic monopoles don't exist, then magnetic monopoles don't exist".
Quantum field theory is very successful experimentally (as successful as epicycles would be with the use of an unlimited hierarchy), but it is notably unsuccessful philosophically; there is no unity of substance in the theory.
Oh dear. Please check your cracpot index before further explicating your personal philosophy.
Relativity and quantum mechanics currently give physicists nightmares. As near as we can tell, both are fantastically accurate descriptions of the world, and both are fundamentally at odds with each other.
From the later parts of your post it's obvious that you're now talking about *special relativity*. It is not in any way at odds with quantum mechanics; in fact, the fusion of relativity and quantum mechanics (something called "quantum field theory") is *the most succesful theory of physics ever developed* (at least when success is measured by how well the theory fits with experiment).
What we don't have is a quantum theory of gravity. We have a very well working *classical* theory of gravity, called "general relativity", which is obviously as much at odds with quantum mechanics as any classical theory is.
Now, when Einstein devised relativity, he based it very heavily on Maxwell's Laws. The Laws are a set of four equations which describe pretty much all electromagnetic phenomena out there. It was the world's first Grand Unified Theory (GUT), in that it unified electricity and magnetism into one package.
That would not be a _GUT_.
And one of Maxwell's Laws ("the divergence of the magnetic field equals zero") has, as a direct consequence, an absolute law: NO MAGNETIC MONOPOLES EXIST.
This is certainly true, but it is trivial to fix this law to handle magnetic monopoles. Remember, you have one Maxwell equation basically stating that
div E = electric charge density
and another, the one that states that no magnetic monopoles exist,
div B = 0
(for the completely unprepared reader: here E and B are the electric and magnetic fields and "div" is a certain sort of an operator that acts on vectors) If you compare these two equations, you'll see *why* the divergence of B is zero: by analogy, div B should just equal the "magnetic charge density", but since there are no magnetic monopoles, the magnetic "charge" density is always zero and div B = 0. In other words, there is no *theoretical* reason why you couldn't write
div B = magnetic charge density
but since the *experiments* tell us that this is always zero, we don't usually bother talking about magnetic charges at all and just set this to zero. If the experiments ever tell us that magnetic monopoles exist, then we'll just have to include these magnetic charge/current terms (which are normally set to zero) in Maxwells equations as well.
So if Maxwell's Laws are wrong and relativity is built heavily on Maxwell's Laws, then there's a tantalizing chance relativity is wrong.
No, there isn't. First of all, including magnetic monopoles the way I outlined above won't make Maxwells theory of electromagnetism in any way incompatible with special relativity. This would be a very minor modification of electodynamics. Second of all, special relativity isn't *based* on electrodynamics at all - ED was an inspiration for Einstein (basically, Maxwells ED is at odds with Newtonian mechanics; Einstein saw this and decided to seek an alternative theory of mechanics that wouldn't be in conflict with it - and found one). If electodynamics ever turned out to be wrong, it wouldn't yet say anything at all about the validity of special relativity.
(OUCH! I thought I hit the preview button! Here's my post again, this time in a readable form.)
If the poster was looking for a first book on QM, Landau and Sakurai are certainly too advanced (for example, even though Sakurai explains even the basic formalism, his discussion is too brief to be useful to anyone not already knowing a lot about QM).
It really doesn't matter that much which book you read at this level. I think the best advice would be to visit a university library or a really good book store and pick the book you like. (Though, if that isn't an option, Griffiths, which was already recommended by many, is a very good first book.) It should cover these topics, in roughly this order:
Wave mechanics: the Schrödinger equation and a zillion solutions; the harmonic oscillator, the hydrogen atom...
The general formalism (Dirac notation and all that)
Spin and angular momentum
Scattering
Perturbation theory
Any book that treats all these should be suitable.
If the poster was looking for a first book on QM, Landau and Sakurai are certainly too advanced (for example, even though Sakurai explains even the basic formalism, his discussion is too brief to be useful to anyone not already knowing a lot about QM).
It really doesn't matter that much which book you read at this level. I think the best advice would be to visit a university library or a really good book store and pick the book you like. (Though, if that isn't an option, Griffiths, which was already recommended by many, is a very good first book.) It should cover these topics, in roughly this order:
- Wave mechanics: the Schrödinger equation and a zillion solutions;
the harmonic oscillator, the hydrogen atom...
- The general formalism (Dirac notation and all that)
- Spin and angular momentum
- Scattering
- Perturbation theory
Any book that treats all these should be suitable.
To continue the SR/GR example: I knew that Einstein developed his theory without knowing about Michelson-Morely.
OK! Sorry if I got a little carried away with my explanation...
The important thing, as I see it, is that the Michelson-Morely experiment provided an experimental validation of one of the postulates of his theory.
Yes. (Or, perhaps more importantly, it provided evidence that the ether theory in which everyone else believed was wrong and forced them to consider other options. The really convincing proofs of SR came from entirely elsewhere...)
OK, so if you think about these experiments from this point of view, then yes, there will be many theories that they'll be able to validate (or invalidate). The most obvious of all is of course GR and its prediction of gravitational waves... but everybody expects GR to be right anyway, so this isn't the thing we're all so worked up about.
I may be repeating myself, but this is going to provide a whole new channel of information about astronomical events, which will help us verify many astrophysical theories. At first, we'll be on the "edge" of just seeing the waves, so we'll only be able to see signals from the most violent things that happen around the universe: colliding black holes or neutron stars and such stuff. That will help us verify our models of these things, like the article says (they're talking about just this stuff), but not any fundamental theory of physics (or at least that's not expected).
Later, if they can improve the accuracy (I'm not an experimentalist, I don't know how far they can take this), there will be many other interesting things we can see. For example, in the far-off future we might be able to see a gravitational wave background produced in the Big Bang (or soon after it), which actually might provide us some information about quantum gravity. (Right now, many people are excited about the new microwave background data we're about to get from the new experiments; there's some talk about whether string theory might be able to predict some of the fine features seen in the microwave background.) But that really is far off in the future...
I wonder if they will be at all able to measure the speed of a graviton with this current setup.
No.
For instance, some spin-2 thermodynamics could be experimentally demonstrated if gravitrons could be isolated and easily detected.
No (see my earlier post on quantum gravity and gravitational waves).
According to current theory, there is absolutely no way we could even begin to dream about detecting individual gravitons, much less confine them. These experiments aren't a step towards this "goal" any more than any other experiment out there: according to current theories of physics (yes, the most fundamental ones), confinement of gravitons is an absolutely unimaginable task for all foreseeable technology.
Compare this with neutrinos. They only interact weakly, through the "weak force" (and, of course, they also interact gravitationally), as opposed to, say, protons and electrons, which interact through the strong force and the electromagnetic force. The important difference is that the weak force is, well, like the name says, weak: the probability of any interaction of neutrinos (with any known form of matter) is much, much lower than the probability of protons or electrons interacting with each other.
Remember that quantum mechanics only predicts probabilities. Imagine a neutrino traveling towards the Earth: it has a very low probability to "collide" with any particles of the Earth, so most likely it will just shoot right through the Earth like it's just empty space. A proton or an electron wouldn't do that (or, at least, this would be very, very improbable): they can also interact through the two stronger forces, which means that they would have a much higher probability to collide with some particle of the Earth. For this reason it takes some incredibly complicated arrangements to detect neutrinos (you need a huge detector to get even a single neutrino collision per day).
Now, while neutrinos can interact through the weak force (and gravitationally), the problem with gravitons is that they can only interact through gravitation. And gravitation is much, much weaker than even the weak force! The difference is actually many, many orders of magnitude larger than the difference between the electromagnetic force and the weak force. So we're not goint to see any gravitons for a very, very long time!
Maybe some time in the future we'll be able to build some galaxy-sized detector in intergalactic space and finally see some gravitons... but, unless the "coming" theory of gravity predicts some totally new effects (and it might), it's really that far off.
What I meant was, could this new data resolve some of the inconsistencies in physics?
Yeah, and the answer still is "not directly".
More (and better) data at the turn of the century helped scientists discover the inadequacy if Newtonian mechanics,
Yes, that's the usual story. But it's not really that accurate.
the constancy of the speed of light,
Actually, this was a theoretical prediction of classical electrodynamics, not something that was first discovered by experiment. Most physicists of that era just didn't like this prediction, so they tried to interpret it through the ether idea - and then later experiments disproved this idea.
I know you've probably heard the story about how the Michelson-Morley experiment left everyone baffled until Einstein came along and explained everything by taking this observed constancy as a basic postulate of a new theory of mechanics. That's a nice story, but it's not what actually happened! There is little evidence that Einstein was even aware of the whole experiment. His first article on the special theory of relativity doesn't refer to it (some parts of it can be interpreted as evidence that Einstein was aware of the experiments, but not very convincingly).
So it's not like some "new and better data" suddenly made everyone realize there was something wrong with the current theories of physics. There were two basic theories of physics, mechanics and electrodynamics, which weren't compatible (unless you made some additional, artificial postulate, ie. ether). Einstein solved this problem by theoretical thought alone by modifying the other theory; he didn't use any experimental data (expect, of course, the data that verified classical mechanics and electrodynamics in the first place).
So, the point of this long explanation is that scientific progress doesn't necessarily follow this simple path of "oh, here's the new data... oops, it doesn't fit our theories, we better invent new ones... oh, here's the new data..." (and, in fact, with the most fundamental theories of physics, it never does).
Right now there is a one similar, big inconsistency in modern physics: quantum mechanics and general relativity aren't "compatible". This is not completely analogous to the situation with the ether and all that: since we have succesfully made all the other classical theories (mechanics, special relativity, electrodynamics) compatible with quantum mechanics, we would expect that general relativity we could similarly quantize general relativity and get a "quantum" theory of gravity. We already know which particular feature of general relativity makes the usual quantization methods fail, so many people think this is just a question of finding the right way to do it.
(In fact, in situations in which this annoying feature of general relativity - its "nonlinearity" - isn't important, we can already make some credible calculations "combining" general relativity and quantum mechanics. The best known example is Hawking radiation.)
And, like I said in my previous post, we're not expecting this experiment to show any "quantum" effects. We have already verified general relativity on this scale (and it works - you can't see any quantum gravitational effects in the motion of planets, for example). If general relativity were to fail on this scale, we should already be able to see quantum gravitational effects in other experiments. So, the only way we could see QG in these experiments would be if GR and QM turned out to be completely wrong... and, even though you all non-physicist out there may not believe me when I say this, this is just not going to happen.
Just like I said earlier, you can safely compare this to classical electrodynamics and light: it doesn't take much experimental accuracy to verify the existence of light (ie. electromagnetic waves), but it does take a lot of work to get to the level where you get to see quantum electrodynamics in action. Similarly (this analogy is actually very close to being exact), there's a long gap between being able to merely detect gravitational waves and seeing quantum gravity in action. Even the former is very difficult to do (as should be evident), so it shouldn't be surprising that nobody expects that the latter is going to happen any time soon ("soon" quite possibly meaning many centuries or even millenia).
Like I said, there is always the possibility that we might be able to see some unexpected things through these gravitational waves, but the waves themselves will be just what classical general relativity predicts (and if they aren't, it will not mean we've hit the quantum theory of gravity; it will mean that GR is completely wrong).
And, of course, most importantly, there are a lot of interesting thing out there waiting to be discovered that just aren't the most fundamental things that exist. Not every discovery can lead to a great revolution in fundamental physics, but that doesn't make the discoveries any less exciting! The big revolutions happen so rarely that if that's all you're interested in, you're not going to get much else than disappointment from science.
(Really, a whole new kind of astronomy is being born! It's going to tell us all sorts of interesting things about the universe, even if it doesn't lead to the Theory of Everything. And that's exciting enough for me!)
wave-particle duality, and the structure of the atom.
Now this is getting closer: the Bohr model was rather directly based on experimental evidence. But the experiments were actually very misleading: they made people believe that some kind of discreteness was essential, which made them develop a theory (originally called quantum mechanics) based on some arbitrary "quantization conditions", while the real theory was actually something completely different.
Now we're stuck with the horribly misleading term "quantum mechanics" and a whole lot of people who think "discreteness" is the most essential feature of the theory. But, umm... this is getting offtopic, so I better stop right now...
No. The waves we're going to see are a prediction of the classical theory of gravitation, general relativity. This is, of course, only an approximation to some "quantum" theory, but on this level of accuracy we're going to see only classical effects.
Compare this with classical electrodynamics (which predicts electromagnetic waves, ie. light): merely detecting gravitational radiation is going to tell you just as much about quantum gravity as seeing sunlight tells you about quantum electrodynamics.
Could it give evidence to bolster string theory?
No.
The results of this experiment should be very interesting.
Yes, but not in the way you seem to be expecting.
No "new" physics is likely to come out of these experiments (at least not directly). The exciting part is, like the article says, that this is going to give us a whole new way of doing astronomy: remember that a century ago the only way to get any information from distant objects was to look at them, but there's a whole lot of objects that are sending stuff at us on wavelengths not visible to the human eye. So, the early astronomers missed many very important things of what we're now able to see.
Being able to observe the whole electromagnetic spectrum has completely revolutionized astronomy in the past 100 years. Just think of cosmic background radiation: for a long time, it was completely missed since nobody was doing astronomy with microwaves. Similarly, there are many interesting things out there that could be sending us a signal through gravitational waves (like, for example, merging black holes) - and soon we'll be able to see that signal and whatever it's telling about these events.
Of course, the resolution will really be of the sort "an event lasting t seconds was recorded...", but we can extract useful information from even this kind of observations, especially if we can combine them with others (like optical telescopes). (This way we may even indirectly discover something totally new.)
"This is why the stars in galaxies don't fly apart as the universe expands. The gravitational force at those scales is much greater than the expansion."
Some nitpicking: this is not right. You can't do this kind of a "strength comparison" between some force and the expansion of the universe. In fact, whether or not some system holds together in the process has absolutely nothing to do with the strength of the attractive forces between its individual parts.
For example, consider yourself just standing on the surface of the Earth. You are bound to the Earth by its gravity. To travel to outer space you would need to somehow obtain enough energy kinetic to climb out of the Earths gravitational well. If you somehow managed to do this and would start traveling around in space with a huge speed (greater than the Earths "escape velocity"), you would still feel the effect of the Earths gravity, but the difference would be that you'd have enough energy to escape the well and travel where ever you'd want to go. Similarly, the Moon is bound to the Earth since it doesn't have enough kinetic energy to escape the Earths potential well.
For another example, consider an electron and a proton traveling around freely in space close to each other. There is of course an attractive force between the two of them. The most important question then is whether they have enough energy to overcome this attractive force and travel freely to infinity or will the attractive force be strong enough to keep them together. If they are moving too fast for the force to hold them together, they'll move around as independent free particles; if they are moving so slowly that the force will always be strong enough keep them together they will form a bound state. (This particular bound state is better known as the hydrogen atom.)
The essential question here is whether or not the system is bound or not: if it is, the distance between its parts will not increase due to the expansion of the universe; if the system isn't bound, the distance will increase. This has really nothing to do with the strength of the interaction, but depends entirely on whether the internal forces are strong enough to hold the system together, given the energies of the internal parts.
The Milky Way and Andromeda are gravitationally bound in this sense: they don't have enough energy to escape each others potential wells, so they don't recede from each other when the universe expands. While the space between them expands, gravity will still always have the same distance-dependence, so it will keep the galaxies together exactly the same way.
(The collision is likely to change all this, though. At least some parts of our two galaxies are going to acquire enough kinetic energy to escape the new system, whatever that is going to look like.)
"Now I can see a large galaxy colliding with a smaller cluster of dwarfs or whatever it was - but at the end of the article they talk as if it's a fairly well-known fact that the Milky Way and Andromeda will collide at some point in the distant future."
Yes, they will collide.
"Now, I seem to remember the classic marker-spots-on-a-balloon explanation that so long as the universe is expanding each galaxy continues to get further and further away from each at a high speed (near light speed but not quite?)."
Remember that in the real world galaxies aren't fixed marks drawn on a balloon. They are free to move around space any way they want to in addition to this "cosmic recession" due to expansion of space. So, in terms of the balloon analogy, the galaxies can move freely around the surface of the balloon while it's inflating; their velocity will be the sum of this recession velocity (which they would have if they weren't moving on the balloon) and the velocity at which they are moving on the balloon.
Another important thing to note is that not every galaxy is receding at the same velocity. If you measure the velocities from one galaxy, those galaxies which are further away from this one will appear to have a larger velocity. The recession speed is given by a formula known as Hubble's law:
v = H*d
where v is the velocity, H is a constant (known as the Hubble constant - Google will give you a numerical value) and d is the distance from the Milky Way (or any other galaxy where you could be measuring these things) to the other galaxy. In addition to this velocity (which won't nowhere near light speed unless the other galaxy is *very* far away), the galaxy can have any other velocity due "ordinary" movement through space, but these velocities are randomly determined (they are due to collisions with other galaxies and such "ordinary" things), so on average galaxies will tend to follow Hubble's law and recede from us. Also, since the recession velocity increases in proportion to distance, distant galaxies will follow this law much better than nearby galaxies, so there will be much fewer exceptions.
OK, so that should be clear by now. Now, forget everything I just said! The above is all true and nice to know, but it isn't at all relevant for the Milky Way and Andromeda. I just wanted to make a few other things clear before moving on to this one...
Andromeda and the Milky Way do not recede at all due to expansion of space. They are bound together by gravity, just like (for example) the Earth and the Moon. If you still like to think in terms of the balloon analogy, imagine that some of the marks (which would have to be something a bit more substantial than pen marks) would be tied together with a piece of rubber band. As the balloon inflates, the marks would try to separate from each other, but the band would pull them back together. So, things that have some kind of a force holding them together ("bound systems") don't expand while most of the universe does.
In fact, speaking about galaxies in the balloon analogy is somewhat misleading, since they are usually gravitationally bound to many other galaxies, so galaxies really aren't the objects Hubble's law is all about. For example, the Milky Way is bound to Andromeda, the Magellanic Clouds and a huge number of other galaxies which have much more cryptic names. Together these are all known as the "local group" of galaxies. Some of its members are much further away from us than Andromeda and still not receding from us.
Oh, and I must say one thing: the balloon analogy is nice and quite illustrative, but taking it too seriously can lead to some pretty horrible misconceptions. You shouldn't trust too much on any conclusions drawn from it.
Slashdot Mirror
By several moderators?!?
My head hurts.
I thought you enjoyed sitting in the sauna then rolling naked in the snow...
:-/
Hey! That guy is *Norwegian*. They don't have saunas. The Norwegians bathe in oil. The poor Norwegians have the biggest oil reserves in Europe and then we hear them complain about the climate, which is not even cold. Damn those ridiculous oily Norwegians!
No, just kidding. I love cold! The coldest nude-rolling-in-the-snow I've had was at about -50 C and I still liked that. But this winter has been about the crappiest one ever, it's something like -0.5 C right now.
In fact, most cultures will eat anything, as the international success of McDonalds well proves.
Finns will eat a bitter oil,
Well, since this already degenareted to the level of national slurs... I can see that you learned to read at an American school.
The rapeseed oil that I use is not bitter. Not even fresh rapeseed tastes very bitter (I grew up in the middle of rape fields, so I tried rape many times and actually found it rather pleasant) (no puns intended, here, naturally), not even the varieties that weren't grown for human consumption. IMHO, of course.
but Americans and Canadians won't touch it, except in the altered form marketed as Canola Oil.
Americans won't touch rapeseed oil, unless someone sells it to them as something else than rapeseed oil? OK, I can believe that...
The difference between what is today called "canola oil" and "rapeseed oil" in North America is that canola oil is marketed for cooking and rapeseed oil is marketed (if it is marketed) for industrial use. For this reason, the oil needs to meet some FDA/[insert Canadian equivalent] restrictions before it can be called canola oil. The reason the-breed-originally-called-Canola was bred that a certain acid in rapeseed oil was considered unhealthy in the US, so someone set out to breed a variety that would automatically have a low amount of that acid. The name was catchy (and the old name probably gave the marketing drones nightmares), so nowadays all rapeseed oil sold for human consumption is called canola oil in North America.
That's it. Canola isn't "an altered version of rapeseed oil", it's just rapeseed oil that's deemed to have acceptable levels of that particular acid (and everything else someone might have considered harmful to humans). Dunno about English speaking countries in general, but here in Finland we don't feel like we need a separate word for "rapeseed oil that's approved by the bureaucrats". (It might also have something to do with the fact that our words for rape and rape don't resemble each other.)
and that rapeseed oil was used to lubricate steam engines.
Sure. I don't understand why it so often surprises people, but many things that are useful in the kitchen are also useful for other things. There's no law of chemistry that states that industrial lubricants have to taste bad.
I see reading a few bits from Wikipedia and answering without actually knowing anything about the subject now gets you modded up. See the article on rapeseed to actually learn something about the subject; it's less nonsensical.
Rapeseed oil has traditionally been the most important cooking oil in many countries, especially here in the north where you can't grow corn, peanuts, soybeans, palm trees or pretty much anything (I live in Finland...). You need some processing to make it edible, but it's been one of the most significant sources of vegetable oil long before Canola was bred. Most of the world hasn't even heard of canola oil but is happy to eat rapeseed oil. I just fried some stuff using some.
No. The Higgs is a critical part of the Standard Model, that is, the best current theory of particle physics. It's not a part of the basic theory of quantum mechanics at all. If the Higgs is not found, that'll mean trouble for the Standard Model but not at all for quantum mechanics.
and the boson is not found, the basic foundation of quantum mechanics will have to be questioned,
Again, no. Finding or not finding the Higgs will not say anything at all about quantum mechanics, it will only say something about the Standard Model of particle physics. The SM is naturally built on quantum mechanics, but proving it wrong will not say anything about quantum mechanics; there's still no reason to assume that the correct theory wouldn't be some other theory based on quantum mechanics.
For comparison, think of Newton. He introduced both the general laws of mechanics (the stuff about forces and such) and a particular theory of a phenomena, gravity, in the context of his new mechanics. If it would've turned out that his law on the force of gravity had been wrong, it wouldn't have yet meant that there would've been something wrong with the concept of force. His theory of gravity was a separate theory expressed in the context of his theory of mechanics, just like the theories of particle physics are separate theories expressed in the context of quantum mechanics.
Quantum mechanics is a very abstract and general theory, the most general theory we have (and *much* more general than classical mechanics). It's just a set of axioms that dictate how the laws of nature must work; the principles of quantum mechanics are actually completely indifferent to what the world is "made of", "particles" or whatever. You can build a wild variety of theories on quantum mechanics, using any entities you can mathematically dream of as the basic building blocks (for example, "particles" as they do on your first QM course or "fields" as they do on your particle physics course).
Err... what prominence? The countries where the communists were truly prominent after WWII ended up in the East bloc; Finland didn't.
Some communists were able to achieve some power immediately after the War with the help of some Soviet meddling, for example through the Allied Control Comission (which in Finland was almost completely made up of Soviet representatives - the other Allies had no demands for Finland), but they never managed to bring Finland to a revolution (and, unlike the communists in some other countries, they had less of an interest in a violent revolution that would've taken Finland into the Soviet Union). Some years after the war it was clear that the communists were no real political power.
There was, still, a rebound in radical leftism after the Continuation War. It's not so hard to explain at all. For example, most of the Finnish cultural elite had been extremely unhappy about fighting together with the Nazis and when the whole truth about them got out (during war time the anti-Nazi press had been silenced, so people didn't know that much about the Germans), they were absolutely shocked. It's not very surprising that many people felt the need to distance themselves from the Nazis as much as possible, even if it meant getting "closer" to the ideology of Finland's worst enemy.
Althought recently in decline, in the last parliamentary elections, the Left Alliance, the successor to the Communist Party, got close to 10% of the vote.
The Left Alliance isn't really "the successor to the Communist Party", but a successor to several leftist parties, the Communists being the most radical ones. The most radical parts of the Communist Party refused to join the Left Alliance and set up the Communist Party again (so there isn't a "successor" to it as such, it's just that almost all of the "ex"-communists joined the LA).
It would be silly to call the Left Alliance people "communists" (but IMHO still not at all silly to call them dumbasses :-)). The actual Communist Party is nothing but a joke today - Donald Duck and the female private organ probably get more votes than the communists.
What the **** we are going to do when the Russians come? :)
We'll offer them some coffee, let them play Tetris on our mobile phones and stick a 20 euro bill in their pockets if they promise to go home.
I mean, 20 euros ought to be enough for any Russian soldier...
Actually, the quality of soldiers was different, or rather the quality of the leadership. The Finns still had a lot of officers who had training and field experience from the old Imperial Russian army, but on the Russian side that talent had all been lost in the revolution, and even after that Stalin's purges had taken a heavy toll on the Red Army. Stalinism massively hurt almost everything important to any Soviet efforts, from science to the military, when the political leadership interfered with everything and replaced competent people with idiots that made bigger promises.
And...
Four, defending your homeland gives you some extra boost compared to simply invading some other country.
The Soviets had also expected there to be a lot of Finnish communists who would defect and greet the Red Army as some great liberator, but there weren't because the Soviets had already killed them. There had been a lot of communists in Finland, but most of them had moved to the Soviet Union (this was not a big deal for a Finnish communist: there were a lot of ethnic Finns living in the Soviet Union, so it was just the border between a capitalist bourgeois democracy and the great socialist wonderland) and the paranoid Soviets had, of course, executed almost all of them as spies or unreliables. (The rumors that not all was well in the wonderland then, naturally, contributed a lot to the Finnish will to fight; for the Finns, it was not just Finland that was at stake, but the fate of Finns as a people.)
Totalitarianism has a real habit of working against itself...
You don't? Well, we certainly do over here in Finland! I just cooled down a pizza outside. Unfortunately (yeah right, mwahaha!) it's not cold enough to properly cool down beer right now, but when it is, we do that, too.
I mean, when it gets down to -20s celcius and you spend a lot of energy heating your house to +20 celcius, then you spend some more energy to cool down the fridge inside the house (although it actually participates in heating up your house), it sounds kind of ridiculous, don't you think ?
No, it doesn't. Your fridge (or anything else) cannot destroy energy, so every bit of energy taken from the electrical socket must end up in the house - and the only thing that a fridge really produces is heat (it doesn't radiate away any energy as light, for example). You have to remember that when you put energy in an object to heat it, you take energy out from it to cool it. If you were to use the outside air to cool things, you'd actually be throwing away some heat that you've paid for - what you suggest would be a waste of energy, not the other way around.
(Of course, it might make sense for you personally to cool things outside, depending on how you're heating your house. My apartment is heated by some waste heat from some factory or power plant or something like that, so I'm not actually directly paying for the amount of heat; it's included in the rent. Cooling things outside would be economical for *me*, but it's always unecological. Not that it matters much either way, but...)
Maybe it wouldn't be of much use for anyone but canadians, russians, norvegian and the like, but still...
Not for most Norwegians. I think most of them live on the coast and there they have the Gulf current heating up the place, so they don't have proper freezing weather. Besides, the Norwegians don't have to worry about some tiny energy savings - they have oil to burn. (Way too much oil! Damn we hate those Norwegians.)
Hmm. The noise from my PC has often made me want to throw it out the window. Now it occures to me that, since I live in Finland, this might actually be a *great* idea!
So special relativity, being non-quantum, is also as much at odds with quantum mechanics as any classical theory too?
No.
Woh, deep!
Not really; this is just an issue with terminology. What's a classical theory and what's a quantum theory? Well, I don't want go into that much detail on a web forum, so lets just grab some simple example, like the point particle.
The classical (Newtonian or relativistic) theory of a point particle is just the "physics" they tought you in high school. The basic objects in this theory have some property called "position" and another one called "velocity", the speed at which the "position" changes; to completely describe one such object you need to specify its "position" with three numbers (assuming we're doing 3D physics) and its "velocity" with another three numbers. That's how you describe a system of classical point particles. Then, when you want to include some actual physics, you introduce "forces" between the particles and apply Newtons laws to see how their velocities change due to these forces.
The quantum theory of point particles still consists of these same properties, "position" and "velocity", but in a very different way. Briefly put, a quantum particle doesn't have a specific position or velocity, but can be in a "superposition" of different positions - you can have a particle sitting here with 36 % probability and there with 24 % probability and so on (and then you'll also have to think of something called the "phase" to completely describe the system, but lets not go into that now).
So, in QM, position and velocity are no longer the basic quantities that you'd directly solve from the laws of physics. Instead, the basic law, "the Scrodinger equation" (for point particle nonrelativistic QM), only gives a "wave function", a mathematical object from which you can calculate the probabilities of observing the particle in different positions and with different velocities. (Then, if you wanted to include some actual physics in the picture, you'd insert something representing interactions in the Schrodinger equation and solve the wave functions.)
That's how it works for the point particle. But it works the same way for any sort of a system. For example, we might have objects called "fields", which are things that have some value (which might a single number, a vector or something else) at every point in spacetime. To handle this classically, you need an infinite number of numbers (much more than the 2*3 you need with point particles!), but otherwise it works similarly. Again, the quantum version of is different, in the expected way (although in the actual study of quantum fields you'd run into many unexpected things).
The point is, you have a bunch of numbers (called "degrees of freedom") that describe some sort of a system; once you have decided in this way what kind of a system you have, you can do either classical mechanics or quantum mechanics with it. (Of course, it really isn't this simple, but I just want to bring out a certain point, so maybe a little simplification can be allowed.)
Now, is special relativity a classical or a quantum theory? You can sort of argue that it's neither: it's just a statement about the (fixed) geometry of spacetime. There are no numbers, "degrees of freedom", that go along naturally with it. It doesn't concern any sort of a system; it just tells you a fixed thing, a symmetry that you need to include in your equations if you want them to comply with this "special relativity". In this sense you can talk of "special relativistic QM" or "special relativistic mechanics" (or "special relativistic anything") and mean the same thing - that you're doing physics in a "special relativistic" ("Minkowskian") spacetime.
What's general relativity, then? Well, it's just the same as SR, but this time the geometry of spacetime is dynamical i
I didn't forget. Did you notice that part where I said that "...then we'll just have to include these magnetic charge/current terms (which are normally set to zero) in Maxwells equations as well."
If I read you correctly, you'd want to assume that electromagnetism can be built on a single vector potential and then conclude (from the theory that you get this way) that magnetic monopoles don't exist. Sorry, but this is utter nonsense. If you had taken a basic course on electromagnetism, you'd know that the ability to describe electromagnetism with a single vector potential depends on the fact that the divergence of the magnetic field vanishes and it - just like I said in my previous post - only vanishes if magnetic monopoles don't exist.
In other words, assuming that one vector potential is enough is equivalent to assuming that magnetic monopoles don't exist. Your argument really says nothing else than "if you assume that magnetic monopoles don't exist, then magnetic monopoles don't exist".
Quantum field theory is very successful experimentally (as successful as epicycles would be with the use of an unlimited hierarchy), but it is notably unsuccessful philosophically; there is no unity of substance in the theory.
Oh dear. Please check your cracpot index before further explicating your personal philosophy.
From the later parts of your post it's obvious that you're now talking about *special relativity*. It is not in any way at odds with quantum mechanics; in fact, the fusion of relativity and quantum mechanics (something called "quantum field theory") is *the most succesful theory of physics ever developed* (at least when success is measured by how well the theory fits with experiment).
What we don't have is a quantum theory of gravity. We have a very well working *classical* theory of gravity, called "general relativity", which is obviously as much at odds with quantum mechanics as any classical theory is.
Now, when Einstein devised relativity, he based it very heavily on Maxwell's Laws. The Laws are a set of four equations which describe pretty much all electromagnetic phenomena out there. It was the world's first Grand Unified Theory (GUT), in that it unified electricity and magnetism into one package.
That would not be a _GUT_.
And one of Maxwell's Laws ("the divergence of the magnetic field equals zero") has, as a direct consequence, an absolute law: NO MAGNETIC MONOPOLES EXIST.
This is certainly true, but it is trivial to fix this law to handle magnetic monopoles. Remember, you have one Maxwell equation basically stating that
div E = electric charge density
and another, the one that states that no magnetic monopoles exist,
div B = 0
(for the completely unprepared reader: here E and B are the electric and magnetic fields and "div" is a certain sort of an operator that acts on vectors) If you compare these two equations, you'll see *why* the divergence of B is zero: by analogy, div B should just equal the "magnetic charge density", but since there are no magnetic monopoles, the magnetic "charge" density is always zero and div B = 0. In other words, there is no *theoretical* reason why you couldn't write
div B = magnetic charge density
but since the *experiments* tell us that this is always zero, we don't usually bother talking about magnetic charges at all and just set this to zero. If the experiments ever tell us that magnetic monopoles exist, then we'll just have to include these magnetic charge/current terms (which are normally set to zero) in Maxwells equations as well.
So if Maxwell's Laws are wrong and relativity is built heavily on Maxwell's Laws, then there's a tantalizing chance relativity is wrong.
No, there isn't. First of all, including magnetic monopoles the way I outlined above won't make Maxwells theory of electromagnetism in any way incompatible with special relativity. This would be a very minor modification of electodynamics. Second of all, special relativity isn't *based* on electrodynamics at all - ED was an inspiration for Einstein (basically, Maxwells ED is at odds with Newtonian mechanics; Einstein saw this and decided to seek an alternative theory of mechanics that wouldn't be in conflict with it - and found one). If electodynamics ever turned out to be wrong, it wouldn't yet say anything at all about the validity of special relativity.
Warning: I'm not a professional physics geek.
Well, I am. Trust me, I know what I'm doing. :-)
If the poster was looking for a first book on QM, Landau and Sakurai are certainly too advanced (for example, even though Sakurai explains even the basic formalism, his discussion is too brief to be useful to anyone not already knowing a lot about QM).
It really doesn't matter that much which book you read at this level. I think the best advice would be to visit a university library or a really good book store and pick the book you like. (Though, if that isn't an option, Griffiths, which was already recommended by many, is a very good first book.) It should cover these topics, in roughly this order:
Wave mechanics: the Schrödinger equation and a zillion solutions; the harmonic oscillator, the hydrogen atom...
The general formalism (Dirac notation and all that)
Spin and angular momentum
Scattering
Perturbation theory
Any book that treats all these should be suitable.
If the poster was looking for a first book on QM, Landau and Sakurai are certainly too advanced (for example, even though Sakurai explains even the basic formalism, his discussion is too brief to be useful to anyone not already knowing a lot about QM). It really doesn't matter that much which book you read at this level. I think the best advice would be to visit a university library or a really good book store and pick the book you like. (Though, if that isn't an option, Griffiths, which was already recommended by many, is a very good first book.) It should cover these topics, in roughly this order: - Wave mechanics: the Schrödinger equation and a zillion solutions; the harmonic oscillator, the hydrogen atom... - The general formalism (Dirac notation and all that) - Spin and angular momentum - Scattering - Perturbation theory Any book that treats all these should be suitable.
To continue the SR/GR example: I knew that Einstein developed his theory without knowing about Michelson-Morely.
OK! Sorry if I got a little carried away with my explanation...
The important thing, as I see it, is that the Michelson-Morely experiment provided an experimental validation of one of the postulates of his theory.
Yes. (Or, perhaps more importantly, it provided evidence that the ether theory in which everyone else believed was wrong and forced them to consider other options. The really convincing proofs of SR came from entirely elsewhere...)
OK, so if you think about these experiments from this point of view, then yes, there will be many theories that they'll be able to validate (or invalidate). The most obvious of all is of course GR and its prediction of gravitational waves... but everybody expects GR to be right anyway, so this isn't the thing we're all so worked up about.
I may be repeating myself, but this is going to provide a whole new channel of information about astronomical events, which will help us verify many astrophysical theories. At first, we'll be on the "edge" of just seeing the waves, so we'll only be able to see signals from the most violent things that happen around the universe: colliding black holes or neutron stars and such stuff. That will help us verify our models of these things, like the article says (they're talking about just this stuff), but not any fundamental theory of physics (or at least that's not expected).
Later, if they can improve the accuracy (I'm not an experimentalist, I don't know how far they can take this), there will be many other interesting things we can see. For example, in the far-off future we might be able to see a gravitational wave background produced in the Big Bang (or soon after it), which actually might provide us some information about quantum gravity. (Right now, many people are excited about the new microwave background data we're about to get from the new experiments; there's some talk about whether string theory might be able to predict some of the fine features seen in the microwave background.) But that really is far off in the future...
I wonder if they will be at all able to measure the speed of a graviton with this current setup.
No.
For instance, some spin-2 thermodynamics could be experimentally demonstrated if gravitrons could be isolated and easily detected.
No (see my earlier post on quantum gravity and gravitational waves).
According to current theory, there is absolutely no way we could even begin to dream about detecting individual gravitons, much less confine them. These experiments aren't a step towards this "goal" any more than any other experiment out there: according to current theories of physics (yes, the most fundamental ones), confinement of gravitons is an absolutely unimaginable task for all foreseeable technology.
Compare this with neutrinos. They only interact weakly, through the "weak force" (and, of course, they also interact gravitationally), as opposed to, say, protons and electrons, which interact through the strong force and the electromagnetic force. The important difference is that the weak force is, well, like the name says, weak: the probability of any interaction of neutrinos (with any known form of matter) is much, much lower than the probability of protons or electrons interacting with each other.
Remember that quantum mechanics only predicts probabilities. Imagine a neutrino traveling towards the Earth: it has a very low probability to "collide" with any particles of the Earth, so most likely it will just shoot right through the Earth like it's just empty space. A proton or an electron wouldn't do that (or, at least, this would be very, very improbable): they can also interact through the two stronger forces, which means that they would have a much higher probability to collide with some particle of the Earth. For this reason it takes some incredibly complicated arrangements to detect neutrinos (you need a huge detector to get even a single neutrino collision per day).
Now, while neutrinos can interact through the weak force (and gravitationally), the problem with gravitons is that they can only interact through gravitation. And gravitation is much, much weaker than even the weak force! The difference is actually many, many orders of magnitude larger than the difference between the electromagnetic force and the weak force. So we're not goint to see any gravitons for a very, very long time!
Maybe some time in the future we'll be able to build some galaxy-sized detector in intergalactic space and finally see some gravitons... but, unless the "coming" theory of gravity predicts some totally new effects (and it might), it's really that far off.
What I meant was, could this new data resolve some of the inconsistencies in physics?
Yeah, and the answer still is "not directly".
More (and better) data at the turn of the century helped scientists discover the inadequacy if Newtonian mechanics,
Yes, that's the usual story. But it's not really that accurate.
the constancy of the speed of light,
Actually, this was a theoretical prediction of classical electrodynamics, not something that was first discovered by experiment. Most physicists of that era just didn't like this prediction, so they tried to interpret it through the ether idea - and then later experiments disproved this idea.
I know you've probably heard the story about how the Michelson-Morley experiment left everyone baffled until Einstein came along and explained everything by taking this observed constancy as a basic postulate of a new theory of mechanics. That's a nice story, but it's not what actually happened! There is little evidence that Einstein was even aware of the whole experiment. His first article on the special theory of relativity doesn't refer to it (some parts of it can be interpreted as evidence that Einstein was aware of the experiments, but not very convincingly).
So it's not like some "new and better data" suddenly made everyone realize there was something wrong with the current theories of physics. There were two basic theories of physics, mechanics and electrodynamics, which weren't compatible (unless you made some additional, artificial postulate, ie. ether). Einstein solved this problem by theoretical thought alone by modifying the other theory; he didn't use any experimental data (expect, of course, the data that verified classical mechanics and electrodynamics in the
first place).
So, the point of this long explanation is that scientific progress doesn't necessarily follow this simple path of "oh, here's the new data... oops, it doesn't fit our theories, we better invent new ones... oh, here's the new data..." (and, in fact, with the most fundamental theories of physics, it never does).
Right now there is a one similar, big inconsistency in modern physics: quantum mechanics and general relativity aren't "compatible". This is not completely analogous to the situation with the ether and all that: since we have succesfully made all the other classical theories (mechanics, special relativity, electrodynamics) compatible with quantum mechanics, we would expect that general relativity we could similarly quantize general relativity and get a "quantum" theory of gravity. We already know which particular feature of general relativity makes the usual quantization methods fail, so many people think this is just a question of finding the right way to do it.
(In fact, in situations in which this annoying feature of general relativity - its "nonlinearity" - isn't important, we can already make some credible calculations "combining" general relativity and quantum mechanics. The best known example is Hawking radiation.)
And, like I said in my previous post, we're not expecting this experiment to show any "quantum" effects. We have already verified general relativity on this scale (and it works - you can't see any quantum gravitational effects in the motion of planets, for example). If general relativity were to fail on this scale, we should already be able to see quantum gravitational effects in other experiments. So, the only way we could see QG in these experiments would be if GR and QM turned out to be completely wrong... and, even though you all non-physicist out there may not believe me when I say this, this is just not going to happen.
Just like I said earlier, you can safely compare this to classical electrodynamics and light: it doesn't take much experimental accuracy to verify the existence of light (ie. electromagnetic waves), but it does take a lot of work to get to the level where you get to see quantum electrodynamics in action. Similarly (this analogy is actually very close to being exact), there's a long gap between being able to merely detect gravitational waves and seeing quantum gravity in action. Even the former is very difficult to do (as should be evident), so it shouldn't be surprising that nobody expects that the latter is going to happen any time soon ("soon" quite possibly meaning many centuries or even millenia).
Like I said, there is always the possibility that we might be able to see some unexpected things through these gravitational waves, but the waves themselves will be just what classical general relativity predicts (and if they aren't, it will not mean we've hit the quantum theory of gravity; it will mean that GR is completely wrong).
And, of course, most importantly, there are a lot of interesting thing out there waiting to be discovered that just aren't the most fundamental things that exist. Not every discovery can lead to a great revolution in fundamental physics, but that doesn't make the discoveries any less exciting! The big revolutions happen so rarely that if that's all you're interested in, you're not going to get much else than disappointment from science.
(Really, a whole new kind of astronomy is being born! It's going to tell us all sorts of interesting things about the universe, even if it doesn't lead to the Theory of Everything. And that's exciting enough for me!)
wave-particle duality, and the structure of the atom.
Now this is getting closer: the Bohr model was rather directly based on experimental evidence. But the experiments were actually very misleading: they made people believe that some kind of discreteness was essential, which made them develop a theory (originally called quantum mechanics) based on some arbitrary "quantization conditions", while the real theory was actually something completely different.
Now we're stuck with the horribly misleading term "quantum mechanics" and a whole lot of people who think "discreteness" is the most essential feature of the theory. But, umm... this is getting offtopic, so I better stop right now...
Would this help unify quantum gravity and GR?
No. The waves we're going to see are a prediction of the classical theory of gravitation, general relativity. This is, of course, only an approximation to some "quantum" theory, but on this level of accuracy we're going to see only classical effects.
Compare this with classical electrodynamics (which predicts electromagnetic waves, ie. light): merely detecting gravitational radiation is going to tell you just as much about quantum gravity as seeing sunlight tells you about quantum electrodynamics.
Could it give evidence to bolster string theory?
No.
The results of this experiment should be very interesting.
Yes, but not in the way you seem to be expecting.
No "new" physics is likely to come out of these experiments (at least not directly). The exciting part is, like the article says, that this is going to give us a whole new way of doing astronomy: remember that a century ago the only way to get any information from distant objects was to look at them, but there's a whole lot of objects that are sending stuff at us on wavelengths not visible to the human eye. So, the early astronomers missed many very important things of what we're now able to see.
Being able to observe the whole electromagnetic spectrum has completely revolutionized astronomy in the past 100 years. Just think of cosmic background radiation: for a long time, it was completely missed since nobody was doing astronomy with microwaves. Similarly, there are many interesting things out there that could be sending us a signal through gravitational waves (like, for example, merging black holes) - and soon we'll be able to see that signal and whatever it's telling about these events.
Of course, the resolution will really be of the sort "an event lasting t seconds was recorded...", but we can extract useful information from even this kind of observations, especially if we can combine them with others (like optical telescopes). (This way we may even indirectly discover something totally new.)
"This is why the stars in galaxies don't fly apart as the universe expands. The gravitational force at those scales is much greater than the expansion."
Some nitpicking: this is not right. You can't do this kind of a "strength comparison" between some force and the expansion of the universe. In fact, whether or not some system holds together in the process has absolutely nothing to do with the strength of the attractive forces between its individual parts.
For example, consider yourself just standing on the surface of the Earth. You are bound to the Earth by its gravity. To travel to outer space you would need to somehow obtain enough energy kinetic to climb out of the Earths gravitational well. If you somehow managed to do this and would start traveling around in space with a huge speed (greater than the Earths "escape velocity"), you would still feel the effect of the Earths gravity, but the difference would be that you'd have enough energy to escape the well and travel where ever you'd want to go. Similarly, the Moon is bound to the Earth since it doesn't have enough kinetic energy to escape the Earths potential well.
For another example, consider an electron and a proton traveling around freely in space close to each other. There is of course an attractive force between the two of them. The most important question then is whether they have enough energy to overcome this attractive force and travel freely to infinity or will the attractive force be strong enough to keep them together. If they are moving too fast for the force to hold them together, they'll move around as independent free particles; if they are moving so slowly that the force will always be strong enough keep them together they will form a bound state. (This particular bound state is better known as the hydrogen atom.)
The essential question here is whether or not the system is bound or not: if it is, the distance between its parts will not increase due to the expansion of the universe; if the system isn't bound, the distance will increase. This has really nothing to do with the strength of the interaction, but depends entirely on whether the internal forces are strong enough to hold the system together, given the energies of the internal parts.
The Milky Way and Andromeda are gravitationally bound in this sense: they don't have enough energy to escape each others potential wells, so they don't recede from each other when the universe expands. While the space between them expands, gravity will still always have the same distance-dependence, so it will keep the galaxies together exactly the same way.
(The collision is likely to change all this, though. At least some parts of our two galaxies are going to acquire enough kinetic energy to escape the new system, whatever that is going to look like.)
"Now I can see a large galaxy colliding with a smaller cluster of dwarfs or whatever it was - but at the end of the article they talk as if it's a fairly well-known fact that the Milky Way and Andromeda will collide at some point in the distant future."
Yes, they will collide.
"Now, I seem to remember the classic marker-spots-on-a-balloon explanation that so long as the universe is expanding each galaxy continues to get further and further away from each at a high speed (near light speed but not quite?)."
Remember that in the real world galaxies aren't fixed marks drawn on a balloon. They are free to move around space any way they want to in addition to this "cosmic recession" due to expansion of space. So, in terms of the balloon analogy, the galaxies can move freely around the surface of the balloon while it's inflating; their velocity will be the sum of this recession velocity (which they would have if they weren't moving on the balloon) and the velocity at which they are moving on the balloon.
Another important thing to note is that not every galaxy is receding at the same velocity. If you measure the velocities from one galaxy, those galaxies which are further away from this one will appear to have a larger velocity. The recession speed is given by a formula known as Hubble's law:
v = H*d
where v is the velocity, H is a constant (known as the Hubble constant - Google will give you a numerical value) and d is the distance from the Milky Way (or any other galaxy where you could be measuring these things) to the other galaxy. In addition to this velocity (which won't nowhere near light speed unless the other galaxy is *very* far away), the galaxy can have any other velocity due "ordinary" movement through space, but these velocities are randomly determined (they are due to collisions with other galaxies and such "ordinary" things), so on average galaxies will tend to follow Hubble's law and recede from us. Also, since the recession velocity increases in proportion to distance, distant galaxies will follow this law much better than nearby galaxies, so there will be much fewer exceptions.
OK, so that should be clear by now. Now, forget everything I just said! The above is all true and nice to know, but it isn't at all relevant for the Milky Way and Andromeda. I just wanted to make a few other things clear before moving on to this one...
Andromeda and the Milky Way do not recede at all due to expansion of space. They are bound together by gravity, just like (for example) the Earth and the Moon. If you still like to think in terms of the balloon analogy, imagine that some of the marks (which would have to be something a bit more substantial than pen marks) would be tied together with a piece of rubber band. As the balloon inflates, the marks would try to separate from each other, but the band would pull them back together. So, things that have some kind of a force holding them together ("bound systems") don't expand while most of the universe does.
In fact, speaking about galaxies in the balloon analogy is somewhat misleading, since they are usually gravitationally bound to many other galaxies, so galaxies really aren't the objects Hubble's law is all about. For example, the Milky Way is bound to Andromeda, the Magellanic Clouds and a huge number of other galaxies which have much more cryptic names. Together these are all known as the "local group" of galaxies. Some of its members are much further away from us than Andromeda and still not receding from us.
Oh, and I must say one thing: the balloon analogy is nice and quite illustrative, but taking it too seriously can lead to some pretty horrible misconceptions. You shouldn't trust too much on any conclusions drawn from it.